Naive bitcoiner here.

So what's the deal here? Would this essentially just require everyone to collectively agree that he owned the coins?

Yes it would require a hard fork of bitcoin, which of course would also mean that everyone using bitcoin would have to agree to adopt the new forked version.

Which of course would mean that the entire foundation of bitcoin gets called into question (if courts can move it around against owner's wills) and the value likely takes a big hit.

Really it would be more of getting the developers to settle since they wouldn't be able to make everyone adopt the new fork version.

Right, that’s the only way to make sense of the litigation threats. Squeeze a few hundred thousand out of each dev, settle for a fraction of a penny on the pound.

>The current value in sterling of the digital assets at the Addresses is approximately £3.65bn, ...

I can't wait for the legal system to start interfering with crypto coins. The effects will be interesting to say the least.

Sounds like that could be fun to try an enforce.